1. Field of the Invention
The present invention generally relates to basketball goals that are vertically adjustable in position, and to a lock for locking the goal at any selected vertical height. The present invention more particularly relates to such goals that are vertically adjustable in position by means of a threaded drive screw and a lock for preventing any undesired rotation of the drive screw.
2. Description of the Prior Art
Basketball goals that are present in multi-use gymnasiums are generally movable from a use position to a storage position so that activities other than basketball can proceed without the interference of the basketball goal. Even the use position of a given basketball goal can vary depending upon the age of the basketball game participants. Thus for many years, basketball goals have been vertically positioned by a variety of mechanisms. One such mechanism, shown in Chervenka U.S. Pat. No. 2,916,288, involves two legs that are coupled to the ceiling structure of a gymnasium to define a fixed support that includes parallel tubular sleeves coupled to the two legs. A cross frame is fixed between the tubular sleeves holding a threaded nut. Legs of a movable support are telescopically received in the tubular sleeves. A basketball goal is coupled to the movable support. A transverse brace bar is fixed to the legs below the cross frame of the fixed support. A threaded drive screw extends between the transverse brace bar and the fixed support cross frame. An eye is fixed to the lower end of the drive screw that can receive a crank for rotating the drive screw to adjust the height of the basketball goal in relation to the fixed support. Locking bolts are received in the tubular sleeves and can be tightened against the legs of the movable support to secure the basketball goal at any desired height. The locking bolts are not automatically engaged. Rather, the locking bolts are manipulated by means of C-shaped handles secured to the bolts that can be turned by the same crank used for rotating the drive screw. Through use the C-shaped handles can become deformed or even break so that the locking function of the locking bolts can be lost.
Another mechanism shown in Schroeder et al. U.S. Pat. No. 5,462,269 involves a backboard assembly that is vertically adjustable by rotation of a drive screw having a polygonal drive head on a lower end of the drive screw. A lock structure is provided which is biased to automatically lock onto the drive screw head and is unlocked upon engagement of the drive screw head by a suitable driver. The locking structure is responsive to the attaching and detaching of a driver such that the detaching of the driver from an input of the screw drive allows the biasing element to force the engagement of the lock and the screw drive. The lock can be disengaged by attaching the driver with an upward force sufficient to overcome the biasing element of the lock. The unlocking action requires an upward force which not only is sufficient to overcome the biasing element, the force must also be sufficient to overcome the weight of the driver itself. While the application of the necessary upward force for sufficient time to make a minor adjustment in backboard position is not difficult, some people have found this upward force requirement to be difficult to sustain during the entire length of time sufficient to completely raise or lower the backboard assembly.
There is therefore an unsatisfied need for a backboard assembly that is vertically adjustable having a lock structure that automatically is engaged when the assembly is not being adjusted, yet can easily be unlocked when necessary by the application of only a minor amount of force.